A disposable plastic container and tubing set or fluid circuit is typically used for collecting blood from a donor. The disposable blood collection set includes a venipuncture needle for insertion into the arm of the donor. The needle is attached to one end of a flexible plastic tube which provides a flow path for the blood. The other end of the plastic tube is attached to one or more plastic bags or containers for collecting the withdrawn blood.
The blood collection set may also include a sampling sub-unit. The sampling sub-unit allows for collection of a sample of blood, which sample can be used for testing of the blood. Preferably, the sample is obtained prior to the “main” collection of blood. Collecting the sample prior to the main collection reduces the risk that bacteria residing on the donor's skin where the needle is inserted (i.e., in particular, the small section of detached skin commonly referred to as the “skin plug”) will not enter the collection container and contaminate the blood collected for transfusion. Thus, it is preferred that the blood samples which may include the skin plug, be diverted from the main collection container.
An example of a blood collection set with such a “pre-donation” sampling sub-unit is described in U.S. patent application Ser. No. 09/364,628 filed Jul. 29, 1999, and U.S. patent application Ser. No. 09/492,060 filed Jan. 27, 2000, which are incorporated by reference herein. The collection sets described therein include a needle and a length of tubing, one end of which is attached to the needle and the other end of which is attached to one or more collection containers. The tubing set also includes an additional line which is branched from the main line at a Y-connection site in the tubing set. The branched line is attached to a sampling pouch for collecting a smaller volume of blood from which samples may be obtained.
The sampling sub-unit may further include a pre-attached holder for receiving blood sample vials or tubes. The holder is connected to the outlet port of the sampling pouch and includes a needle in the holder interior. When the blood sample vial is inserted into the holder, the needle pierces the rubber cap (septum) of the vial and blood from the sampling pouch is drawn into the vial. The blood-filled vial is removed from the holder and the procedure may be repeated with as many vials as required.
The blood collection set described above also includes flow control clamps for controlling the flow of biological fluid (e.g., blood) through the set and to the sampling pouch and/or collection container. Flow control clamps commonly used are the Roberts-type clamps, which are well known in the art. The Roberts-type clamps are placed on the tubing line leading to the blood collection container and on the tubing line leading to the sampling pouch. A Roberts-type clamp is typically made from a strip of plastic. The ends of the strip are curved toward each other to provide two “legs” which are adapted to engage each other in a snap-fit, spring relation. The body of the clamp includes a pair of apertures through which the tubing passes.
The clamp further includes a pair of projections or tube contacting members which compress the tubing when the body of the clamp is depressed, thereby restricting flow, through the tube. Clamps of this type are generally described in U.S. Pat. Nos. 3,942,228, 6,089,527 and 6,113,062, all of which are incorporated herein by reference.
The clamps described in these patents also typically include means for locking the legs together and release means which, when actuated by the technician, disengages the locked legs of the flow control clamp. Disengagement of the ends decompresses the tube and permits fluid flow through the flow path. Thus, by selectively opening and closing the different flow paths (by depressing or releasing the clamps), the technician can control the flow of blood from the donor, diverting the blood to the desired container or sampling pouch, as necessary.
In certain instances, however, it may not be desirable to reopen a closed flow path. This may particularly be the case when drawing blood samples from the sampling pouch into sample vials. For example, when the sampling pouch is filled with the required or desired volume of blood (for sampling), the line from the donor to the pouch is typically closed by the Roberts-type clamp, and remains closed as the sampling vials are filled. After clamping the sampling line closed, technicians are further instructed to more permanently seal the line using metal clips or by heat-sealing the line in ways that will be known to those in the field. Sealing the sampling line substantially ensures that airborne bacteria or other contaminants that may enter the set through the sampling sub-unit do not contaminate the remainder of the set, including the needle and tube leading to the collection container. In short, the clips or heat seal provide a sterile barrier to the remainder of the set.
Unfortunately, on occasion, prior to permanently sealing the sampling line, some technicians have been known to unclamp the sampling line in order to draw additional blood into the pouch so that additional sample vials may be filled. However, by doing so, the system becomes “open” and contaminants introduced from the outside environment may enter the system. Current flow control clamps are readily and easily openable, and do not provide a disincentive to drawing additional blood into the sampling pouch. If the clamp could not be so readily released from the closed position, the technician would not have the option of reopening the line but would, hopefully, proceed with permanently sealing the line to form the sterile barrier. Accordingly, it would be desirable to provide a clamp that discourages and substantially prevents the reopening of the sampling or other blood tube line.